33s on 3.55s, IIRC my speedo is off by a good 5mph by 65, and by 85 I'm sure it's off by 10.

I bet you're still getting much better MPGs than other similar vehicles in the same class as an XJ if they were modded the same though.

Still running 33s on 3.55s myself and my XJ still gets significantly better MPG than my 3.9l v6 Dakota on 235s. Specs on the two are almost identical and both are maintained, seafoamed, recent tune ups, ect.

thanks for all the replys guys, decided im just gonna learn to drive the ZJ like an old lady
im a 16 year old kid that just got his license, so as you can imagine, theres been quite a few gas-gulping rocket blasts

The XJ's fuel economy may not impress, but consider this--they're super reliable, super capable, super easy to do your own work on, and they (and their parts) are cheap to maintain (use a larger oil filter and synthetic oil, and oil changes become less frequent, too). I happily accept ho-hum MPG in exchange for all that.

I'm not saying the ZJ doesn't have those factors on its side; the 5.2 is also super reliable and relatively cheap. Yes, the Chrysler transmissions aren't as reliable as an AW4 auto trans, but they're still quite fine.

I say that if you find a 2wd manual XJ (4 cyl or not), and you really want a more efficient DD while still using a Jeep, buy it! A manual 2wd XJ should be able to get more than 20 mpg. Maintain and mod it with MPG in mind, and I'm sure you can really get the MPGs much higher. FastPlastic, a member of EcoModder.com, has modded his/her 4.0 XJ 4x4 to the point of reaching like 26 MPG highway. Some of his/her mods are a bit more involved than just removing the roof rack or sticking to stock sized highway tires, but nothing super extreme.

How are you driving your zj to only get 11 "on a good day?" Put some gears in it and clean the **** out of it and it should get better mpg's. My Ram that had the same engine got 18 mpg and it's entire engine was a poorly taken care of and a POS.

Tune up and clean should go a long way if it hasn't been done in a while or possibly ever.

New:
Spark plugs, wires, filters (air, oil, and fuel), distributor cap and rotor.
Also not a bad idea to go ahead and replace the trans (drain and refill only) fluid and diff fluids in the axles.

I'd also seafoam it. There are a lot of stupid people out there who will tell you it doesn't work or will ruin your motor, and it can, but only if you're stupid about it and go and dump a full can into a system that's never been cleaned.

Here's how I seafoam mine and it's always kept my Jeeps clean and helped with fuel economy if it's been suffering from a lack of maintenance.

Take one can and divide it into the gas tank, oil, and either the intake or the brake booster line.

First I take a 1/3 can and dump it in with my oil. Drive about 20 miles on it then go change the oil and filter. Helps clean out build up but you don't want to leave it in for an extended period of time.

Then I dump a 1/3 can in a full tank of gas as well as a half can with the next two fill ups (from almost empty). Fuel filter change isn't a bad idea after this either since it's likely original. After that I only seafoam the gas tank once a year.

Then I take with the Jeep off, the last 1/3 and dump a small amount in the intake. Maybe half a shot or so. Then I start the Jeep and rev it til it stops blowing white smoke out the tail pipe (there will be a lot of it and should be). Then I shut the Jeep off and repeat til the can is empty. You can do this through the brake booster line as well.

I do all of this about every other or every 3rd oil change and I change my oil about 4 times a year. You could probably do it less frequently if you drive a bit more than I do. Keeps everything nice and clean without putting too much into any one system at a time which can create problems if they've never been cleaned.

If it's never been cleaned then the MPGs you gain back should be pretty noticeable. You'll never gain more than original from this but it helps get back lost fuel economy. Other than that if you want you can start upgrading things like your header, intake, and exhaust for MPGs. No single upgrade will be noticeable but combined they add up, especially if you're someone who takes the time to calculate your MPGs correctly and really watch them.

I run 33x12.5 MTRs on 3.55s and calculate my MPG via GPS and I'm still getting 16 city. Slowing down how I drive, watching my RPMs, ect has helped a lot as well which has been hard for me because I HATE slow drivers and have next to no patience when driving and have the worst road rage lol

There's a difference between wanting good MPG for the class and wanting good MPG compared to a small 4 banger car.

If you're getting 13 mpg in an XJ you're either running big tires, ignorant of what you need to fix/maintain to get more realistic MPGs, or you're flat out too lazy to improve it. EPA estimates for city never dipped under 14 and they're a median calculation and they're 10+ years old. There's no reason a properly maintained XJ with a few performance mods for better fuel economy can't get 17 or higher city MPG.

Lies all lies!!! Normally I couldn't agree more but I can't seem to get better then 13mpg city, although I get 20-21hwy. Iv changed almost everything I can think of. My conclusions are that tons of tiny trips (under a couple miles) destroys mpgs and that's what I mainly do.

__________________
"****, I might **** around and bring the Jeep back No doors on it, flexin' with the seat back"

Half of this thread is invisible on my computer so I guess I'll just stick my opinion in and hope I don't get blasted. I've never owned or driven a 4 Cylinder XJ but from what I hear they are extremely slow and don't don't get good gas mileage for them being a 4 Cylinder. In my opinion, you'd be better off getting the I6 because if you drive it like a Grandma an XJ will gladly give you 20 MPG, I've seen it before in a few friends XJ's. I get a little over 22 because I have a five speed and mine is 2WD though.

I averaged 18.6 MPG on my last trip to Moab with my XJ. Which has 33's on 3:55 gears it was loaded down with tools, spare parts, recovery gear, Cooler full of ice and water, a few cases of water, food, 4 Adults and a toddler , duffle bags full of clothes ................. Not to mention all of my Armor my XJ is a Pig a light foot and good maintenance goes a long way !

my last XJ which was a 99 4dr 5spd 4x4 3.07's got 22-24 on a regular basis on the highway before I added 31's and a 4" lift.
the best tank I ever got was 25 mpg. it was 98% highway using the cruise and I was sitting on a 2" BB and some well worn 30x9.50 mastercraft AT's.

Half of this thread is invisible on my computer so I guess I'll just stick my opinion in and hope I don't get blasted. I've never owned or driven a 4 Cylinder XJ but from what I hear they are extremely slow and don't don't get good gas mileage for them being a 4 Cylinder. In my opinion, you'd be better off getting the I6 because if you drive it like a Grandma an XJ will gladly give you 20 MPG, I've seen it before in a few friends XJ's. I get a little over 22 because I have a five speed and mine is 2WD though.

hey now, don't be knockin one of my jeeps, haha. slow, yes. as for gas mileage, it does good. what i have noticed with mine is it gets the same in town as it does interstate. long trips do better if you take back roads too. the best i ever got was backroading through lots of small towns and a couple of bigger ones and i got 25. and i still off-road the 2wd. been doin it a lot lately, even with street tires. i did however finally drive my 4wd xj through the creek

I have an 89 XJ with the 4.0 auto trans, I put a 4.5 rough country lift with aussi locker in rear running stock 355 gears and 31" mud tires. it has 180k on it now, runs great very smooth . I get avg 14mpg. If I want better fuel mileage I will need to gear it, but don't want to put work in the D35. When i can it will get the ford 8.8 don'texpect great mileage out of something that will give you so much fun.